Blood supply of the head and brain

External carotid branches

Anatomy of the coronary arteries

PDA = posterior descending artery.

80% have right dominant circulation where the RCA turns toward the apex on the posterior aspect of the heart.

Coronary ostia

1 - pulmonary artery, 2 - Right coronary artery , 3 - Tricuspid valve, 4 - Mitral valve, 5 - Left coronary artery, RED start - anterior / right coronary sinus, BLUE start - left coronary sinus, YELLOW star - non-adjacent / non coronary / right posterior coronary sinus.

Branches of the coronary arteries

Coronary veins

Right coronary artery

RCA supplies the right atrium, right ventricles, SA node and AV node.
Arises rom right / anterior coronary sinus. Can arise from upto 4 branches.

Branches of RCA:

• Right conus artery (conus arteriosus)
• Right anterior ventricular branches
• Atrial branches of RCA
• Posterior ventricular arteries
• Right marginal artery

Along its course, the posterior interventricular artery gives rise to septal branches that supply the posterior third of the interventricular septum.

Left coronary artery

Branches of the LCA

• Left conus artery - supplies the outflow tract of the right ventricle and a large part of the anterior free wall of the right ventricle;
• Anterior ventricular arteries (as many as nine of them) - supplies the left ventricle;
• Posterior ventricular branch - supplies the left ventricle;
• Interventricular septal arteries (anterior, inferior) - to the interventricular septum of the heart.

Coronary territories

Spurious biochemistry results

2023BSQ20

Causes of erroneous biochemistry results during sample collection:
Source

Haemolysis falsely elevates AST.
Grossly lipemic specimens elevate AST.

Causes of pseudohyponatremia
Very high protein - Multiple myeloma, Waldenstrom’s macroglolulinaemia, IV Ig administration
Very high lipids - hypertrygliceridaemia in pancreatitis
Sodium is present only in the liquid part of the serum but that machine calculates sodium concentration using the total volume of the sample (a significant porttion of which is occupied by lipid or protein) Source

Causes of psudohypernatremia
Low protein (eg Critically ill patients) -> Spuriously high Na+
More common than hyperprotinaemia associated spurious hyponatremia.

Serum is the liquid that remains after the blood has clotted. Plasma is the liquid that remains when clotting is prevented with the addition of an anticoagulant.

Pseudohyperkalemia
• In vitro hemolysis [10]
• Fist clenching during phlebotomy [11,12]
• Undue delay in processing blood samples [13]
• Inappropriate storage temperature of blood samples [13]
• Potassium contamination of blood samples [14,15]
and also
Thrombocytosis > 500,000 (activated platelet release K+ and serum is separated by clotting)
Very high WBC
Some red cell membrane defects

PseudoHyperphosphatemia
can be spurious in cases of hyperproteinemia (eg, in multiple myeloma or macroglobulinemia), dyslipidemia, hemolysis, or hyperbilirubinemia.
Heparin contamination

Pseudohypercalcemia

Defined as high total calcium with normal ionized calcium.
Only ionized calcium is physiologically active.

Causes of pseudhypercalcemia
Incr. Albumin or gamma glogulins (increased calcium bound to protein)
Other reported causes of pseudohypercalcaemia include multiple myeloma or M-protein disorder (secondary to avid calcium binding properties of certain paraproteins) thrombocythaemia (probably in vitro release of calcium from excessive number of abnormally activated platelets) hyperlipidaemia (method-dependent artefactual error by spectrophotometry) Source

Effect of tourniquet on electrolyte measurement:

A random slideshare presentation

The phlebotomist should not leave the tourniquet on the patient’s arm for longer than a minute. This increased pressure against the vessel walls allows plasma and small molecules to flow through capillary walls and into the tissue. This process is known as hemoconcentration; it results in a relative increase in the number of red blood cells as well as higher-molecular-weight compounds in the sample drawn. With prolonged tourniquet application time, test results such as albumin, cholesterol, coagulation proteins, and red cell count are falsely increased (Section 3.05.8.4). Source

Carotid barrorecetors

2023BSQ#22
They are baroreceptors.
Cardiopulmonary - "low pressure" baroreceptors are located at entrace of SVC and ICV to atrium.
Have more effect of blood pressure than heart rate.

Located in

• carotid body at bifurcation of internal and external carotid arteries -> goes in a branch of glossopharyngeal neve called carotid sinus nerve)
• (and in the aortic arch) -> goes in the Vagus nerve

Reflex arc for BP control:

Afferent limbs projec to Nucleus of tractus solitarium -> excitatory projections to vagal nucleus AND GABAergic inhibitory projections to sympathetic centers.
Therefore, increased BP -> incr. baroreceptor dischargre freq -> increased vagal tone and decr. sympathetic outlfow.
Effect: Vasodilation, venodilation, bradycardia => hypotension

Afferent limb arises from the carotid baroreceptors and terminates in the vagal nucleus and vasomotor center in the medulla.
Efferent limb: Vagus nerve AND inhibition of sympathetic outflow.

• Granulomatous diseasee
• regarding necrosis